Wetland is a multifunctional ecosystem in the earth, wetlands possess irreplaceable and enormous ecological functions and serve as an essential life supporting system. how to apply the new and high technology to the study of wetland has become the key point in wetland study area in our country. RS, GIS and GPS technology provide a new method for resource and ecological environment monitor. In this paper, the problem and development trend of 3S technology are discussed. Application of 3S technique in the study of wetland environment of Dongting Lake are described. The wetland monitor ways and technique route are introduced. The beach and water area information were gained.the dynamic changes of water were evaluated objective and quantitative. Finally, we point out the difficulties of wetland monitor of Dongting Lake.